Has spent his entire career at the Climatic Research Unit (CRU) of the University of East Anglia, most of it in charge of assembling the past 160 years of global temperature records. Appointed sole director of the unit in 2004. Temporarily stepped aside in the wake of the publication of 13 years of the unit's emails. "I know I'm on the right side and honest, but I seem to be telling myself this more often recently."

Steve McIntyre

Mathematician, former Canadian minerals prospector and, since 2003, full-time amateur scourge of climate science through his ClimateAudit website. "CRU's policies of obstructing critical articles in the peer-reviewed literature and withholding data from critics have unfortunately placed issues into play that might other wise have been settled long ago."

Mike Mann

Physicist-turned-paleoclimatologist. Moved from University of Virginia to Penn State University in 2004. Chief creator of the controversial "hockey stick" graph showing global temperatures over the past 1,000 years, based on a range of proxies such as tree rings. Co-founder of the RealClimate website. "This crowd of charlatans… look for one little thing they can say is wrong, and thus generalise that the science is entirely compromised."

Raymond Bradley

Climatologist at the University of Massachusetts, Amherst. Co-author with Mann and Malcolm Hughes, a British-born tree-ring specialist at the University of Arizona, of key early papers on the hockey stick. "As for thinking that it is 'better that nothing appear, than something unacceptable to us'… as though we are the gatekeepers of all that is acceptable in the world of paleoclimatology, [this] seems amazingly arrogant."

Keith Briffa

Tree-ring researcher since 1977 at CRU, where he is currently deputy director. Helped develop the Yamal tree-ring data sets. Early clashes with Mann mellowed into a long collaboration. Recently suffering serious illness. "I know there is pressure to present a nice tidy story… but in reality the situation is not quite so simple."

Judy Curry

Climate scientist, Georgia Institute of Technology. Caught up in rows about climate change and hurricanes after Katrina in 2005. Subsequently renounced "tribalism" in climate science and sought common ground with critics. "Climate tribes were established in response to the politically motivated climate disinformation machine… to circle the wagons and point the guns outward in an attempt to discredit misinformation."

Mike Hulme

Former researcher at CRU and founding director of the Tyndall Centre for Climate Change Research at the University of East Anglia. Interested in how climate change is represented in culture, history and the media. Recent author of Why We Disagree About Climate Change. "It is possible that some areas of climate science have become sclerotic… too partisan, too centralised. The tribalism that some of the leaked emails display is something more usually associated with… primitive cultures."

Doug Keenan

A Canadian former financial trader on Wall Street and in the City of London. More recently, pursued a series of disputes with climate scientists, mostly about tree ring data. Accused Phil Jones and Wei-Chyung Wang of "fraud" for their handling of data from weather station locations in China. "It is unacceptable that the scientist who disseminates a data product on which international treaties are based… should actively seek to suppress information that calls the quality of the data into question."

Hubert Lamb

Father of modern climatology and charismatic founder of the CRU in 1972. Developed early theories about a medieval warm period and little ice age, and proposed the world was on the verge of a new ice age. Recruited Jones, Wigley and others, but later criticised what he saw as their simplistic theories of man-made climate change. "Increasing the carbon dioxide in the Earth's atmosphere – the end product of all our burning of fossil fuels and of vegetation – should raise the world's temperature, although the effect may be smaller, perhaps very much smaller, than is usually supposed."

Lord Lawson

Senior Conservative politician and Chancellor of the Exchequer between 1983 and 1989. Recent campaigner against mainstream arguments on climate change, describing them as scientifically dubious and economically ruinous. Founded the Global Warming Policy Foundation in late 2009. "Proper scientists, scientists with integrity, wish to reveal their data and all their methods. They do not require freedom of information requests."

Ross McKitrick

Environmental economist at the University of Guelph, Canada. Senior fellow at the Fraser Institute. Collaborator with Michaels and McIntyre. "The key ingredient in most of the studies that have been invoked to support the hockey stick, namely the Brif fa Yamal series, depends on the influence of a woefully thin subsample of trees and the exclusion of readily available data for the same area."

Pat Michaels

Climatologist at the University of Virginia. Fellow at right-wing thinktanks the Cato Institute and George C Marshall Institute. Virginia State Climatologist. Recipient of funds from fossil fuel companies for projects such as his World Climate Report, published since 1994, and his "advocacy science consulting firm", New Hope Environmental Services. Rhetorical scourge of mainstream climate scientists, especially Santer and Mann. Author of books such as Meltdown: The predictable distortion of global warming by scientists, politicians and the media. "The truth is that what we sceptics say is always pilloried by the climate modellers, and then adopted as their own five years later."

Sir Muir Russell

Former head of the Scottish civil service and vice-chancellor of the University of Scotland. Appointed by the University of East Anglia to chair inquiry into Climategate. Most famous north of the border for his stewardship of the building project for the new Holyrood parliament building, which went massively over budget. "There are some very straightforward integrity issues to resolve."

Gavin Schmidt

Climate scientist at Nasa's Goddard Institute for Space Studies. Runs the RealClimate website, where he discovered the hacked emails had been uploaded in November 2009. Has vigorously defended Mann, Jones and others caught up in the Climategate saga. "Gravity isn't a useful theory because Newton was a nice man."

Kevin Trenberth

Climate scientist at the National Centre for Atmospheric Research in Boulder, Colorado. Made enemies among sceptics by linking hurricane intensity to climate change in the wake of Hurricane Katrina in 2005. "The fact is we can't account for the lack of warming, and it's a travesty that we can't."

Hans von Storch

Meteorologist and director of the Institute for Coastal Research in Geesthacht, Germany. "Soft" sceptic who nonetheless resigned as editor-in-chief of the journal Climate Research following publication of a sceptical paper he saw as methodologically flawed. "The authors of the damaging emails would be wise to stand back from positions as reviewers and participants in the IPCC process. The journals Nature and Science must review their quality-control measures and selection criteria for papers."

Wei-Chyung Wang

Climate researcher at the University at Albany in New York. Long-time collaborator with Jones on analysing Chinese temperature data. Accused by Keenan of scientific fraud over his contribution to a paper with Jones published in 1990. Exonerated by his university after an inquiry. "When we started on the paper we had all the station location details in order to identify our network, but we cannot find them any more."

Tom Wigley

Australian-born climate scientist. Director of CRU from 1978 to 1993. More recently at the University Corporation for Atmospheric Research in Boulder, Colorado. Counsellor, critic and father figure in many of the emails. "Why, why, why did you … not simply say this right at the start?"